| 摘要 |
PURPOSE:To produce titled glass having large positive or negative refractive index gradients by subjecting the alkali metal ions in SiO2-R2O type rod-like glass to ion exchanging with another alkali metal ions. CONSTITUTION:SiO2-R2O rod-like glass contg. 0-30wt% (by weight, hereinafter the same) TiO2, 0-30% Gd2O3, 0-30% La2O3, 0-22% Y2O3, and R2O (R is 1 or >=2 kinds among Li, Na, K) and contg. 5-42% the above-mentioned components except R2O in total, and if TiO2 is <=5%, contg. >=5% Gd2O3 or >=10% La2O3+ Y2O3 is dipped in a molten salt which is heated to the temp. from near the refracting point of said glass up to the transition point and contains alkali metal ions differing from the alkali metal ions in said glass, whereby ion exchanging is effected and the concn. gradient of the different alkali ions differing in the refractive index is formed in the radial direction of the glass. |
